We propose to explore the potential of human and bovine hemoglobins as oxygen carriers for transfusional fluids. The aim is to obtain highly purified indissociable tetramers of the two hemoglobins with an oxygen affinity compatible with oxygen transport in vivo. The research will involve the development of the necessary compounds, full analyses of their physico-chemical and functional properties, and initial testing of their storage stability and retention time in small animals. One-step chemical reactions will be used for obtaining the desired hemoglobin derivatives, using limited and specific chemical modifications, so as to avoid formation of products with high antigenic activity. Two compounds already obtained by cross-linking bovine hemoglobin with bis-dibromosalicyl-fumarate will be extensively purified and analyzed for their functional properties and sites of cross-links. New treatments will be designed for human hemoglobin whose cross-linked products have an oxygen affinity higher than that desirable in transfunctional fluids.